Factor in worst case scenario and hopefully the math still works out in your favor. 

Assuming all 2 bedroom units, and assuming getting $700/month for them (leaving $163 for utilities) gross monthly rent would be ~$11,200Using pretty standard expenses, and a USDA loan, my numbers show this losing almost $10,000 a year.If I do some eraser math and make construction costs all-in at $75 per square foot, it winds up making around $12,000 year (with a CoC of around 10% using USDA money.)

There are also some neighborhoods of Lakeland that are significantly less desirable, so be sure to travel there and do your homework before making any purchase decisions.

and can you give a bit detail if you would about the math?

You'll have to do some math to remove a portion to account for the depreciation you were taking while as a rental, but your CPA can take care of that.

Basically emptying the vast majority of my cash into a single home.  Work

I have a friend looking at places for me out there, but want to make sure I'm doing my homework. 

.~$250/unit current increase on all 12 units = $36,000 current additional NOI / 7% cap = $514,000 x 75% LTV = $386,000 current cash out.Someone check my math...it's happy hour here...Need to determine if you have any loan prepayment penalties and other refi costs to add to the math above.

Obviously you have some issues to be addressed around the differences between your math and the seller's.  

Do your homework, figure out if this strategy is legal, ethical and fits your skillset and resources, then make your decision.Long story short: The absolute first thing you should do is find a local RE attorney who understands Sub2 deals and take their word over anything you read here (as great a resource as this is, no one here is your lawyer.)Good luck!